Printers such as laser printers and video printers, copying machines, facsimile machines and all-in-one printers with the functions of these printers and machines employ various image-forming devices utilizing electrophotography. Electrophotographic image-forming devices are equipped with various rollers. Examples of such rollers may include conductive rollers with electric conductivity or semiconductivity, and elastic rollers with a relatively low hardness. The electrically conductive rollers may include, for example, charge rollers for uniformly charging image carriers such as photoreceptors, developing rollers for carrying and conveying a toner to supply the toner to image carriers, toner-supplying rollers for supplying a toner to a developing roller while charging the toner, and fixing rollers for fixing a toner that has been transferred to a recording material, such as recording paper, to the material. These various rollers are usually different in their properties such as hardness and electric resistivity, depending on the function and/or uses of each roller.
For Example, Patent document 1 discloses “an electrically semiconductive member that includes an ionic liquid” for such electrically conductive rollers. Specifically, it teaches “a charge roller that includes a salt of methylimidazolium, and a vinyl monomer or a (meth)acrylate” in a working example.
Also, Patent document 2 teaches “an electrically conductive member for electrophotographic instruments including an electrically conductive composition for electrophotographic instruments, for at least a part of the electrically conductive member, which requires components (A)-(C), wherein the components are:    (A) a matrix polymer,    (B) at least one electrically conductive filler selected from the group consisting of a metal oxide, a metal carbide, and carbon black with a DBP adsorption of 100 mL/g or more, and    (C) an ionic liquid.
Patent document 2 specifically discloses a developing roll having a base layer including silicone polymer and 1-hexyl-3-methylimidazoliumtrifluoromethane sulfonate in Working Example 16.
When the conditions of the area surrounding the site on which an image-forming device is placed are changed, those of the inside of the device are changed accordingly. As a result, the properties of an electrically conductive roller installed in the device may sometimes be changed and the roller may not function sufficiently with originally designed performance.
For example, a developing roller, when the humidity surrounding it decreases, is not capable of supplying a toner with a predetermined amount of electrostatic charge to an image carrier, which causes a situation where unnecessary toner is fixed to a printed image such as a solid white print, which may also be called solid print. The unnecessary toner on the printed image is called fogging. This situation is remarkably experienced especially when a color image is printed after a monochrome image is printed. As explained hereinbefore, when the conditions of the area surrounding a roller installed in an image-forming device are changed, for example, the humidity around a developing roller is lowered, a desired image may not be obtained.